/* Sobel
 * <Description>
 * Displays result of the Sobel method for image processing run on an image.
 * <Usage>
 * javac Sobel.java Picture.java Luminance.java
 * java Sobel picture.jpg
 * <References>
 * http://introcs.cs.princeton.edu/java/31datatype/Luminance.java.html
 * http://introcs.cs.princeton.edu/java/stdlib/Picture.java.html
 * CIS201L-2014-Summer Dr. Sloan
 * @author
 * Dan Latham
 * <l3li3l@torguard.tg>
 * @version 0.0.1
 *
 */
import java.awt.Color;
public class Sobel
{
	public static int multiply(int[] filter, Color[] bynine)
	{
		int a = 0;
		for (int i = 0; i < filter.length; i+=1)
		{
			Color z = bynine[i];
			int y = z.getRed();
			y = y*filter[i];
			a += y;
		}
		return a;
	}
	public static Picture sobel(Picture initpicture, Picture resultpicture)
	{
		int[] filter1 = {-1, 0, 1,
						-2, 0, 2,
						-1, 0, 1};
		int[] filter2 = {1, 2, 1,
						0, 0, 0,
						-1, -2, -1};
		int y0 = initpicture.height();
		int x0 = initpicture.width();
		//get and set color of each pixel
		for (int x = 0; x < x0; x+=1)
		{
			for (int y = 0; y < y0; y+=1)
			{
				//start at top left, iterate down to bottom right
				//declare boundary pixels first(default case)
				Color initcolor1 = new Color(255,255,255);
				Color initcolor2 = new Color(255,255,255);
				Color initcolor3 = new Color(255,255,255);
				Color initcolor4 = new Color(255,255,255);
				Color initcolor5 = initpicture.get(x,y);
				Color initcolor6 = new Color(255,255,255);
				Color initcolor7 = new Color(255,255,255);
				Color initcolor8 = new Color(255,255,255);
				Color initcolor9 = new Color(255,255,255);
				//System.out.println(initcolor5);
				//top left
				try
				{
					initcolor1 = initpicture.get(x-1,y-1);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//top middle
				try
				{
					initcolor2 = initpicture.get(x,y-1);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//top right
				try
				{
					initcolor3 = initpicture.get(x+1,y-1);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//middle left
				try
				{
					initcolor4 = initpicture.get(x-1,y);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//middle right
				try
				{
					initcolor6 = initpicture.get(x+1,y);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//bottom left
				try
				{
					initcolor7 = initpicture.get(x-1,y+1);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//bottom middle
				try
				{
					initcolor8 = initpicture.get(x,y+1);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				//bottom right
				try
				{
					initcolor9 = initpicture.get(x+1,y+1);
				}
				catch(IndexOutOfBoundsException A)
				{
					continue;
				}
				Color[] bynine = {initcolor1, initcolor2, initcolor3, initcolor4, initcolor5, initcolor6, initcolor7, initcolor8, initcolor9};
				int Gx = multiply(filter1, bynine);
				int Gy = multiply(filter2, bynine);
				int colornum =(int) Math.abs(255-Math.sqrt((Gx*Gx)+(Gy*Gy)));
				if (colornum > 255) colornum=255;
				//System.out.println(colornum);
				Color colorgrey = new Color(colornum,colornum,colornum);
				resultpicture.set(x,y,colorgrey);
				
			}
		}
		return resultpicture;
	}
	
	public static Picture ggrayscale(Picture picture)
	{
		int y0 = picture.height();
		int x0 = picture.width();
		//get color of each pixel, convert to grayscale, set color to gray
		for (int x = 0; x < x0; x+=1)
		{
			for (int y = 0; y < y0; y+=1)
			{
				java.awt.Color initcolor = picture.get(x,y);
				java.awt.Color graycolor = Luminance.toGray(initcolor);
				int r = graycolor.getRed();
				int b = graycolor.getBlue();
				int g = graycolor.getGreen();
				
				java.awt.Color newcolor = new java.awt.Color(r,g,b);
				picture.set(x, y, newcolor);
			}
		}
		return picture;
	}
	
	public static void main(String[] args)
	{
		Picture initpicture = new Picture(args[0]);
		Picture resultpicture = new Picture(initpicture.width(),initpicture.height());
		initpicture = ggrayscale(initpicture);
		resultpicture = sobel(initpicture, resultpicture);
		resultpicture.show();
	}
}